The present invention relates to methods and systems for applying a laser to the natural human crystalline lens to address cataracts, opacifications in the lens, clear lens extraction, removal of natural lens material, use of lens replacement materials and combinations of these. The present invention further relates to methods for determining the shape and position of the natural human crystalline lens and cornea relative to a laser device so as to provide an enhanced method and system for applying a laser to the lens and cornea. The present invention additionally relates to systems and methods that provide predetermined, precise and reproducible laser shot patterns for creating a capsulotomy having a predetermined and precise shape that is reproducible from patient to patient and surgeon to surgeon.
In general, presbyopia is the loss of accommodative amplitude. In generally, cataracts are areas of opacification of the ocular lens which are sufficient to interfere with vision. Other conditions, for which the present invention is directed, include but are not limited to the opacification of the ocular lens.
Presbyopia most often presents as a near vision deficiency, the inability to read small print, especially in dim lighting after about 40-45 years of age. Presbyopia, or the loss of accommodative amplitude with age, relates to the eyes inability to change the shape of the natural crystalline lens, which allows a person to change focus between far and near, and occurs in essentially 100% of the population. Accommodative amplitude has been shown to decline with age steadily through the fifth decade of life.
Cataracts, or the condition when the natural crystalline lens becomes opaque and clouds vision, occurs in millions of people per year and are treated effectively with surgical techniques, such as ultrasonic phacoemulsification pioneered by Kelman 30 years ago. Although the techniques have been refined over the years, safety concerns from ocular trauma, especially to the corneal endothelium from the ultrasonic energy required to break up a hardened cataract is undesirable; especially for those with a compromised corneal endothelium, such as those with Fuchs Dystrophy. Moreover, the use of lasers in the treatment of cataracts has a further issue. Cataracts scatter light, including laser light, and thus, can prevent a laser treatment beam from having the desired tissue effect. Moreover, the light scattering effect of cataracts and other opacifications can make optically determining the position and shape of the lens difficult. Accordingly, as provided in detail in this specification herein improvements in the determination of the lens position and shape, as well as, in the delivery of lasers to lens tissues including the lens capsule, cataractous and opacified tissues are provided.
The established treatment for cataracts is the removal of the opacified human crystalline lens and its replacement with an IOL. In general, IOLs consist of a small plastic lens with plastic side struts, called haptics, to hold the lens in place within the capsular bag inside the eye. Exemplary types of IOLs include monofocal lenses, multifocal IOLs which provide the patient with multiple-focused vision at far and reading distance, and accommodative IOLs which provide the patient with visual accommodation. The flexible nature of many IOLs enables them to be rolled and/or folded up for insertion into the capsule. Examples of IOL are found in U.S. Pat. Nos. 7,188,949, 6,849,091, 5,699,142 and 5,607,472, the disclosures of which are incorporated herein by reference. Commercially available IOLs that, by way of example, may benefit from the present invention are CRYSTALENS and ACRYSOF RESTOR.
A schematic representation of the shape and general structure of an example of an accommodating IOL, along the lines of a CRYSTALENS, is provided in FIG. 2. This IOL has a lens structure 202, hinges 203 located adjacent to the lens structure 202 and haptics 204, which contact the lens capsule 201. The overall shape of this IOL would be non-geometric. As used herein the term “non-geometric shape” refers to shapes other than circles and ellipses, including squares and rectangles. As used herein the term “geometric shape” refers to circles and ellipses.
The CRYSTALENS IOL was developed by Eyeonics and is presently provided by Bausch & Lomb. It is at least in part believed to be disclosed in U.S. Pat. No. 6,849,091. Further information regarding its structure and efficacy is provided by Food and Drug Administration (FDA) PMA P030002 and related documents to that PMA file. The FDA approved indicated use for CRYSTALENS was in part: “The Crystalens™ Model AT-45 Accommodating IOL is intended for primary implantation in the capsular bar of the eye for visual correction of apkakia in adult patients in whom a cataractous lens has been removed and is intended to provide near, intermediate, and distance vision without spectacles. The Crystalens™ IOL provides approximately one diopter of monocular accommodation.” (Nov. 14, 2003 PMA P030002 at Part 2, Summary of Safety and Effectiveness Data, ¶ INDICATIONS FOR USE).
Thus, the CRYSTALENS is an example of an FDA approved accommodating IOL. The term “FDA approved accommodating IOL” refers to any IOL that has obtained FDA approval having an indicated use that provides for accommodation, regardless whether such IOL is actually being employed for such an approved use.
The ACRYSOF RESTOR IOL is provided by Alcon. It is at least in part believed to be disclosed in U.S. Pat. No. 5,669,142. Further information regarding its structure and efficacy is provided by FDA PMA P040020 and related documents to that PMA file. The FDA approved use for RESTOR was in part: “AcrySOF® ReSTOR® IOLs are indicated for the visual correction of aphakia secondary to removal of a cataractous lens in adult patients with and without presbyopia, who desire near, intermediate and distance vision with increased spectacle independence. The lens is intended to be placed in the capsular bag.” (Apr. 24, 2004, PMA P040020, at Part 2, Summary of Safety and Effectiveness Data, ¶ INDICATIONS).
Thus, the RESTOR is an example of an FDA approved IOL for near, intermediate and distance vision. The term “FDA approved IOL for near, intermediate and distance vision” refers to any IOL that has obtained FDA approval having an indicated use that provides for near, intermediate and distance vision, regardless whether such IOL is actually being employed for such an approved use. The CRYSTALENS would also be an example of an FDA approved IOL for near, intermediate and distance vision. Moreover, the RESTOR and CRYSTALENS are examples of FDA approved IOLs that reduce and/or eliminate the need for spectacles.
The removal of the opacified natural crystalline lens and replacement with a lens replacement material, such as an FDA approved IOL, presently employs a capsulorhexis and/or a capsulotomy procedure. A capsulorhexis generally consists of the removal of a part of the anterior lens capsule and the creation of a hole or opening in the lens capsule, that results from at least in part a tearing action. A capsulotomy generally consists of a cutting of the lens capsule, without or with minimum tearing of the capsule. Thus, to remove the opacified natural lens material, the lens capsule is opened. There are several known techniques for performing a capsulorhexis and a capsulotomy.
One of these capsulorhexis techniques is a can opener approach. This approach uses a small bent needle to make small incisions around the anterior lens capsule to create an opening in the lens through which the lens could be removed. This technique quite often results in the opening in the lens capsule having ragged edges. Another of these techniques is a Continuous Curvilinear Capsulorhexis (CCC). CCC uses the same type of bent needle to begin the tear in the anterior lens capsule and then uses this needle and/or special forceps which are manually pulled to create a generally circular hole in the lens capsule. CCC, in comparison to the can opener approach, reduces the ragged edge around the opening in the lens that occurred with using the can opener technique. However CCC does not eliminate the formation of these ragged edges and there presence is dependent upon surgical skill and technique.
The use of a Fugo plasma blade to create the hole in the anterior capsule may also be used. This technique is referred to as a capsulotomy. The Fugo plasma blade is a hand held device and was originally utilized in dentistry. It is an electro magnetic device that focuses its energy on a blunt cutting filament. Information regarding the Fugo plasma blade can be found in FDA PMA K063468, K001498, K041019, and K050933.
To date is it believed that all prior techniques and apparatus and in particular all prior FDA approved apparatus for creating an opening in the anterior capsule of the lens, have to varying degrees given rise to irregular shapes, ragged edges, jagged edges, or tags in or along the edge of the opening, and/or combinations of these edge features. Moreover, it is believed that all of these prior techniques and apparatus, which are performed by hand, in general can only produce cuts or holes in the shape of a circle or an ellipse, i.e., they can only be used to provide geometric shapes and cannot be used to provide non-geometric shaped cuts. Further, because these are hand held devices the shape of these cuts varies from patient to patient and surgeon to surgeon. Thus, it is not believed that these hand held devices and non-automated techniques can provide the precise predetermined capsulotomy of the present invention.
The presence of the above described edge features, the inability to create precise predetermined and reproducible shaped cuts and the variability associated with prior techniques and apparatus for performing capsulotomies and capsulorhexises are individually and collectively undesirable and can present difficulties and problems, especially with the use of accommodative IOLs. Furthermore, the limited number of shapes for capsulotomies and capsulorhexis and the variability associated with these prior techniques is believed to be an impediment to the development of new accommodative IOLs. It is further believed that this limited number of shapes and variability is an impediment to the amount of accommodation that can be obtained from presently known IOLs and the instances where little to no accommodation is realized by the patient.